Exothermically heated molten metal pouring nozzle



July 16, 1968 J. B. CAHOON, JR, ET AL 3,392,888

EXOTHERMICALLY HEATED MOB-THEN METAL POURING NOZZLE Filed April 22, 1966 JOHN B.CAHOON,JR. AND WELDON J. GARDNER INVENTORS Hm LwmQA Bu -Q.

THEIR ATTORNEYS United States Patent 3,392,888 EXOTHERMICALLY HEATED MOLTEN METAL POURIN-G NOZZLE John B. Cahoon, Jr., Thornburg Borough, and Weldon J. Gardner, Greentree Borough, Pa., assignors to Vesuvius Crucible Company, Swissvale, Pa., a corporation of Pennsylvania Filed Apr. 22, 1966, Ser. No. 544,610 12 Claims. (Cl. 222-566) ABSTRACT OF THE DISCLOSURE A nozzle for pouring molten metal comprising a refractory element having a bore through which molten metal is adapted to flow and means disposed about and outside of the refractory element comprising exothermic material rendered active to emit heat by the heat of molten metal flowing through the bore whereby to reduce the thermal loss outwardly from the refractory element and thereby minimize freezing of metal in the bore. The means disposed about the refractory element may be in the form of a sleeve applied to the exterior of the refractory element. The sleeve may be in sections appliable laterally to the refractory element with means joining the sections. The exothermic material may comprise a mixture of refractory material, oxidizable metal in a state of subdivision and oxidizing agent. The refractory material may be fire clay and the oxidizable metal may be aluminum. The oxidizing agent may be present in an amount less than stoichiometric for the oxidation of the oxidizable metal, the nature and relative quantities of the exothermically reacting ingredients being such as to produce a temperature of at least about 1000 C.

The refractory element may be surrounded by a layer of exothermic refractory material with a layer of insulating material thereabout. A metal sheath may be disposed about the layer of insulating material. The means disposed about the refractory element may extend beyond the outflow end of the refractory element.

The nozzle may be in a tundish or in a bottom pour ladle. The tundish or ladle may comprise a container lined with refractory material having an opening through its bottom and a nozzle for pouring molten metal therefrom mounted in the opening.

This invention relates to an exothermically heated molten metal pouring nozzle. The nozzle may be employed in any system in which molten metal is to be delivered in a controlled stream by pouring or teeming. For example, the nozzle may be employed in a tundish use-d in continuous casting or in a bottom pour ladle employed for teeming molten metal into ingot molds.

In pouring molten metal in a controlled stream through a nozzle either in continuous casting or in teeming of the molten metal into ingot molds it is important to obtain a uniform pouring rate and a uniform cross-section of the molten metal stream. Such uniformity is not obtained if metal freezes in the nozzle or at the nozzle outlet as the frozen metal restricts the outflowing stream. The problem is especially critical in the pouring of killed steel, such as steel killed with aluminum. The practice heretofore has been to burn out the frozen metal, called icicles, With an oxygen lance which may damage the nozzle bore resulting in non-uniformity of the cross-sectional area and delivery rate of the outflowing stream of molten metal.

We have devised a nozzle for pouring molten metal which obviates the disadvantages heretofore encountered. Our nozzle comprises a refractory element having a bore through which molten metal is adapted to flow together with means disposed about the refractory element com- 3,392,888 Patented July 16, 1968 prising exothermic material rendered active to emit heat by the heat of molten metal flowing through the bore whereby to reduce the thermal loss outwardly from the refractory element and thereby minimize freezing of metal in the bore. The means disposed about the refractory element are preferably in the form of a sleeve applied to the exterior of the refractory element. Such means may be in sections appliable laterally to the refractory element with means joining the sections to form a sleeve.

The exothermic material preferably comprises a mixture of refractory material, oxidizable metal in a state of subdivision and oxidizing agent. The refractory material is preferably fire clay, desirably highly porous fire clay. The oxidizable metal is preferably aluminum although other oxidizable metals, such, for example, as zirconium and magnesium, may be employed, or a mixture of two or more oxidizable metals may be used. The oxidizing agent is preferably an alkali metal salt such as a nitrate, perchlorate or chromate, for example, sodium nitrate. The oxidizing agent is preferably present in an amount less than stoichiometric for the oxidation of the oxidizable metal, the nature and relative quantities of the exothermically reacting ingredients being such as to produce a temperature of at least about 1000 C.

In our preferred nozzle structure the refractory element is surrounded by a layer of exothermic refractory material with a layer of insulating material thereabout. A metal sheath is preferably disposed about the layer of insulating material. Preferably the exothermic material extends beyond the outflow end of the refractory element to inhibit freezing of metal at the nozzle outlet. As above indicated our improved nozzle may be applied to a tundish or a bottom pour ladle or any system in which molten metal is to be delivered in a controlled stream. A tundish or ladle constructed in accordance with our invention may comprise a container lined with refractory material having an opening through its bottom and our improved nozzle for pouring molten metal from the tundish or ladle mounted in the opening.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred embodiment thereof proceeds.

In the accompanying drawings we have shown a present preferred embodiment of the invention in which:

FIGURE 1 is a fragmentary diagrammatic vertical cross-sectional view through a tundish equipped with our improved nozzle; and

FIGURE 2 is a horizontal cross-sectional view taken on the line IIII of FIGURE 1.

Referring now more particularly to the drawings, FIG- URE 1 shows a fragmentary section of a conventional tundish 26 provided with a stopper rod assembly and having a nozzle structure in accordance with our invention. The steel Wall 27 and bottom 5 of the tundish are lined with the usual refractory brick and mortar 6. A vertical stopper rod assembly 7 has a stopper head 8 which is adapted to seat into the inlet 9 of the refractory element 10 having a bore 19 through which molten metal is adapted to flow and which is the functional element of the nozzle. The nozzle element 10 has a flangelike body 25 at its upper end and a depending shank 13 extending downward through a circular hole 11 in the bottom 5 of the tundish. The hole 11 is dimensioned so as to permit a flange 12 at the bottom of the nozzle shank 13 to pass through the bottom hole 11 and also to provide for the support of the nozzle body 25 on a shoulder 14 of the bottom 5 surrounding the hole 11. Refractory material 15 seals the nozzle body 25 to the refractory brick 6.

A heater sleeve 17 shown as being comprised of two sections or units 20 fitting smoothly to the outer cylindrical surface 16 of the nozzle shank 13 is supported on the nozzle flange 12 and extends downwardly to a point somewhat below the bottom surface 18 of the nozzle element 10.

In FIGURE 2 the nozzle shank 13 and heater sleeve 17 are shown in horizontal cross section. The nozzle shank 13 forms an uninterrupted teeming bore 19 tapered or cylindrical as shown and is enclosed by the heater sleeve 17 comprising the two sections or units 20 identical to each other as shown, each of which is comprised of a layer of exothermic refractory material 21, a layer of insulating material 22 and a semicylindrical steel sheath 23, with locking devices 24 which may be compression buckles.

To install, the nozzle element 10 is positioned in a cold tundish 26 of conventional design except that the diameter of the hole 11 in the bottom of the tundish is made to accommodate the nozzle shank 13 and to support the nozzle element as aforementioned. The usual refractory (ramming mix, for example) is used to seal the nozzle element 10 into the refractory 6 of the tundish. The tundish is then dried and preheated in the usual manner. The teeming or continuous casting operation, as the case may be, may be commenced whereafter the sections or units of the heater sleeve 17, which sections or units are quick locking, may be applied and secured in position. This may be accomplished by tongs or manually with gloved hands while the molten metal is flowing through hte nozzle. An exothermic reaction in the heater sleeve 17 is initiated by heat from the molten metal flowing through the nozzle. The heat supplied by the exothermic material maintains the nozzle shank at a high enough temperature to inhibit freezing of metal therein, and the portion of the heater extending below the bottom of the nozzle shank inhibits freezing of metal at the nozzle outlet.

In teeming operations not all heats are of uniform size or take equal pouring time; and, since the inherent nature of the exothermic reaction limits the amount of heat generated for a given quantity of oxidizable material, it may be desirable to remove the burnt out heater sleeve and replace it with a new sleeve without interrupting the metal flow.

While we have shown and described a present preferred embodiment of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

We claim:

1. A nozzle for pouring molten metal comprising a refractory element having a bore through which molten metal is adapted to flow and means disposed about and outside of the refractory element comprising exothermic material rendered active to emit heat by the heat of molten metal flowing through the bore whereby to reduce the thermal loss outwardly from the refractory element and thereby minimize freezing of metal in the bore.

2. A nozzle for pouring molten metal as claimed in claim 1 in which the means disposed about the refractory element are in the form of a sleeve applied to the exterior of the refractory element.

3. A nozzle for pouring molten metal as claimed in claim 1 in which the means disposed about the refractory element are in sections appliable laterally to the refractory element with means joining the sections to form a sleeve applied to the exterior of the refractory element.

4. A nozzle for pouring molten metal as claimed in claim 1 in which the exothermic material comprises a mixture of refractory material, oxidizable metal in a state of subdivision and oxidizing agent.

5. A nozzle for pouring molten metal as claimed in claim 4 in which the refractory material is fire clay and the oxidizable metal is aluminum.

6. A nozzle for pouring molten metal as Claimed in claim 4 in which the oxidizing agent is present in an amount less than stoichiometric for the oxidation of the oxidizable metal, the nature and relative quantities of the exo-thermically reacting ingredients being such as to produce a temperature of at least about 1000 C.

7. A nozzle for pouring molten metal as claimed in claim 1 in which the refractory element is surrounded by a layer of exothermic refractory material with a layer of insulating material thereabout.

8. A nozzle for pouring molten metal as claimed in claim 7 having a metal sheath about the layer of insulating material.

9. A nozzle for pouring molten metal as claimed in claim 1 in which the means disposed about the refractory element extend beyond the outflow end of the refractory element. 1

10. A tundish having therein a nozzle for pouring molten metal from the tundish as claimed in claim 1.

11. A bottom pour ladle having therein a nozzle for pouring molten metal from the ladle as claimed in claim 1.

12. A tundish or ladle comprising a container lined with refractory material having an opening through its bottom and a nozzle for pouring molten metal from the tundish or ladle as claimed in claim I mounted in the opening.

References Cited UNITED STATES PATENTS 3,220,860 11/ 1965 Robiette et al. 106-44 3,341,092 9/1967 Finn 222-566 STANLEY H. TOLLBERG, Primary Examiner. 

